While formwork removal after concreting is essential, timing is crucial to avoid impacting the concrete’s color. Prolonged formwork contact can lead to variations in shade, affecting the structure’s aesthetics.
For long-span concrete structures, achieving sufficient strength to bear self-weight doesn’t eliminate the risk of creep deflection. This time-dependent deformation can occur even after formwork removal, necessitating the introduction of re-propping. However, leaving these props in place for extended periods can be detrimental as accumulating creep loads may overstress them, potentially leading to structural failure.
Therefore, meticulous planning is required to strike a balance. Formwork should be removed promptly to avoid discoloration, but not before the concrete has gained adequate strength. Subsequently, re-propping should be implemented to mitigate creep deflection, yet these temporary supports should be removed as soon as the concrete’s long-term strength and stability are ensured.
The key lies in understanding the unique requirements of each project, considering factors like concrete mix design, environmental conditions, and structural characteristics. By carefully managing the timing of formwork removal and re-propping, engineers and contractors can ensure the structural integrity and aesthetic appeal of long-span concrete structures.